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. 2008 Jun 11;130(23):7198-9.
doi: 10.1021/ja801514m. Epub 2008 May 14.

Enantioselective thiourea-catalyzed additions to oxocarbenium ions

Sarah E Reisman  1 , Abigail G Doyle, Eric N Jacobsen
Affiliations

Enantioselective thiourea-catalyzed additions to oxocarbenium ions

Sarah E Reisman et al. J Am Chem Soc. .

Abstract

Asymmetric, catalytic reactions of oxocarbenium ions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbenium ion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest enantioselectivities, with the optimal structure being derived from enantioenriched 2-arylpyrrolidine derivatives.

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Figures

Figure 1
Figure 1
Addition of tetrasubstituted silyl ketene acetals to provide substituted isochromans.
Scheme 1
Scheme 1
Enantioselective addition to reactive cationic species: hydrogen-bond catalysis by anion-binding
See this image and copyright information in PMC

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